It’s a post-boot authentication bypass exploit. Any post-boot authentication bypass exploit against TPM-only sealed BitLocker effectively bypasses it. The user doesn’t have a key to start with in this setup, just the machine.

This exploit is cool but there are similar exploits discovered in any given year and nothing really reeks of a backdoor; this one seems to be gaining attention mostly because Microsoft’s robo-call level initial response caused the researcher to dramatically crash out.